U.S. patent number 4,944,781 [Application Number 07/378,745] was granted by the patent office on 1990-07-31 for gas chromatograph/autosampler coupling assembly.
This patent grant is currently assigned to Schering Corporation. Invention is credited to Christopher R. Banfield, Donald A. Ruggirello.
United States Patent |
4,944,781 |
Ruggirello , et al. |
July 31, 1990 |
Gas chromatograph/autosampler coupling assembly
Abstract
An assembly for coupling a Hewlett-Packard Model HP 7673A
autosampler mounted on a mounting plate to a Varian VISTA 6000
Model gas chromatograph having an injection site, includes a first
bracket secured to the gas chromatograph on one side of the
injection site and a second bracket secured to the gas
chromatograph on the opposite side of the injection site, with the
mounting plate secured to and mounted on the first and second
brackets so as to permit access to the injection site by the
autosampler; and securement screws for securing the mounting plate
on the brackets.
Inventors: |
Ruggirello; Donald A. (Sunrise,
FL), Banfield; Christopher R. (Plantation, FL) |
Assignee: |
Schering Corporation
(Kenilworth, NJ)
|
Family
ID: |
23494381 |
Appl.
No.: |
07/378,745 |
Filed: |
July 12, 1989 |
Current U.S.
Class: |
73/23.41; 96/103;
96/106 |
Current CPC
Class: |
G01N
30/24 (20130101) |
Current International
Class: |
G01N
30/24 (20060101); G01N 30/00 (20060101); B01D
053/02 (); G01N 030/88 () |
Field of
Search: |
;55/67,197,386
;73/23.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Varian Vista 6000 Gas Chromatograph Manual. .
Hewlett-Packard 7673A Autosampler Manual. .
Varian Vista 402 Data System Manual. .
Hewlett-Packard 3393A Integrator Manual..
|
Primary Examiner: Spitzer; Robert
Attorney, Agent or Firm: Magatti; Anita W. Nelson; James R.
Miller; Stephen I.
Claims
What is claimed is:
1. An assembly for coupling an autosampler mounted on a mounting
plate, to a gas chromatograph having an injection site, said
assembly comprising:
bracket means for mounting said mounting plate to said gas
chromatograph, said bracket means being secured to said gas
chromatograph adjacent injection site so as to permit access to
said injection site by said autosampler; and
securement means for securing said mounting plate on said bracket
means.
2. An assembly according to claim 1; wherein said securement means
includes two holes in said bracket means, two holes in said
mounting plate which are in alignment with said two holes of said
bracket means, and screw means extending through said two holes of
said mounting plate and said two holes of said bracket means for
securing said mounting plate on said bracket means with a two-point
securement.
3. An assembly accoring to claim 2; wherein said bracket means
includes a first bracket and a second bracket secured to said gas
chromatograph on opposite sides of said injection site, said first
bracket including a first one of said holes and said second bracket
including a second one of said holes.
4. An assembly according to claim 1; wherein said gas chromatograph
includes a septum nut assemby at said injection site, said
autosampler includes an injector having a base with an opening, and
said mounting plate includes an opening, with said septum nut
mating in said opening in said base of siad autosampler through
said opening in said mounting plate.
5. An assembly according to claim 1; wherein said mounting plate
includes an opening and a spacer secured to said mounting plate and
extending into said opening, said autosampler includes an injector
having a base with spring means for engaging with said spacer
through said opening in said mounting plate to removably secure
said injector on said mounting plate, and said bracket means
includes an angled cut-out section is alignment with said spacer to
permit access of said spring means under said spacer.
6. An assembly according to claim 5; wherein said bracket means
includes a first bracket and a second bracket secured to said gas
chromatograph on opposite sides of said injection site, said first
bracket including an inner edge facing said injection site and said
angled cut-out section extending in said first bracket from said
inner edge.
7. An assembly according to claim 1; wherein said mounting plate
includes an arcuate slot, and said autosampler includes an injector
having an alignment pin extending into said arcuate slot when said
injector is mounted on said mounting plate.
8. An assembly according to claim 1; wherein said mounting plate
includes a first stabilizing plate secured thereto and depending
from the underside thereof, and said bracket means includes a first
cut-out section for receiving said first stabilizing plate to
stabilize said mounting plate and said injector on said bracket
means.
9. An assembly according to claim 8; wherein said mounting plate
includes a second stabilizing plate secured thereto and depending
from the underside thereof, and said bracket means includes a
second cut-out section for receiving said second stabilizing plate
to stabilize said mounting plate and said injector on said bracket
means.
10. An assembly according to claim 9; wherein said bracket means
includes a first bracket and a second bracket secured to said gas
chromatograph on opposite sides of said injection site, said first
bracket including said first cut-out section and said second
bracket including said second cut-out section.
11. An assembly according to claim 1; wherein said bracket means
includes a first bracket and a second bracket secured to said gas
chromatograph on opposite sides of said injection site.
12. An assembly according to claim 11; wherein
said first bracket includes:
an inner edge facing said injection site; an opposite outer edge;
an angled cut-out section extending from said inner edge;
a first cut-out section extending from said outer edge;
a first hole for receiving screw means for securing said first
bracket to said gas chromatograph; and
a second hole for receiving screw means for securing said mounting
plate on said first bracket; and
said second bracket includes:
an inner edge facing said injection site;
an opposite outer edge;
a second cut-out section extending from said inner edge of said
second bracket;
a third hole for receiving screw means for securing said second
bracket to said gas chromatograph; and
a fourth hole for receiving screw means for securing said mounting
plate on said second bracket.
13. An assembly for coupling a autosampler to a gas chromatograph
having an injection site, said assembly comprising:
mounting plate means for holding said autosampler;
bracket means for mounting said mounting plate means to said gas
chromatograph, said bracket means being secured to said gas
chromatograph adjacent said injection site so as to permit access
to said injection site by said autosampler; and
securement means for securing said mounting plate means on said
bracket means.
14. An assembly according to claim 13; wherein said securement
means includes two holes in said bracket means, two holes in said
mounting plate means which are in alignment with said two holes of
said bracket means, and screw means extending through said two
holes of said mounting plate means and said two holes of said
bracket means for securing said mounting plate means on said
bracket means with a two-point securement.
15. An assembly according to claim 14; wherein said bracket means
includes a first bracket and a second bracket secured to said gas
chromatograph on opposite sides of said injection site, said first
bracket including a first one of said holes and said second
including a second one of said holes.
16. An assembly according to claim 13; wherein said gas
chromatograph includes a septum nut assembly at said injection
site, said autosamper includes an injector having a base with an
opening, and said mounting plate means includes an opening, with
said septum nut mating in said opening in said base of said
autosampler through said opening in said mounting plate means.
17. An assembly according to claim 13; wherein said mounting plate
means includes an opening and a spacer secured to said mounting
plate means and extending into said opening, said autosampler
includes an injector having a base with spring means for engaging
with said spacer through said opening in said mounting plate means
to removably secure said injector on said mounting plate means, and
said bracket means includes an angled cut-out section in alignment
with said spacer to permit access of said spring means under said
spacer.
18. An assembly according to claim 17; wherein said bracket means
includes a first bracket and a second bracket secured to said gas
chromatograph on opposite sides of said injection site, said first
bracket including an inner edge facing said injection site and said
angled cut-out section extending in said first bracket from said
inner edge.
19. An assembly according to claim 13; wherein said mounting plate
means includes an arcuate slot, and said autosampler includes an
injector having an alignment pin extending into said arcuate slot
when said injector is mounted on said mounting plate means.
20. An assembly according to claim 13; wherein said mounting plate
means includes a first stabilizing plate secured thereto and
depending from the underside thereof, and said bracket means
includes a first cut-out section for receiving said first
stabilizing plate to stabilize said mounting plate means and said
injector on said bracket means.
21. An assembly according to claim 20; wherein said mounting plate
means includes a second stabilizing plate secured thereto and
depending from the underside thereof, and said bracket means
includes a second cut-out section for receiving said second
stabilizing plate to stabilize said mounting plate means and said
injector on said bracket means.
22. An assembly according to claim 21; wherein said bracket means
includes a first bracket and a second bracket secured to said gas
chromatograph on opposite sides of said injection site, said first
bracket including said first cut-out section and said second
bracket including said second cut-out section.
23. An assembly according to claim 13; wherein said bracket means
includes a first bracket and a second bracket secured to said gas
chromatograph on opposite sides of said injection site.
24. An assembly according to claim 13; wherein said autosampler
includes an injector, tray means for holding a plurality of samples
and conduit means for connecting the samples to the injector; and
said mounting plate means includes horizontal mounting plate
section means for securing said mounting plate means to said
bracket means and for holding said injector thereon, horizontal
securing plate section means for holding said tray means thereon,
and vertical plate section means for connecting said horizontal
mounting plate section means with said horizontal securing plate
section means.
25. An assembly for coupling an autosampler to a gas chromatograph
having an injection site, said gas chromatograph including a septum
nut assembly at said injection site, said autosampler including an
injector having a base with an opening, spring means extending from
said base and an injector pin extending from said base, said
assembly comprising:
mounting plate means for holding said autosampler, said mounting
plate means including:
a first opening for permitting said septum nut to mate in said
opening in said base of said autosampler;
a second opening;
a spacer secured to said mounting plate means and extending into
said second opening;
an arcuate slot for receiving said injector pin when said injector
is mounted on said mounting plate means;
a first stabilizing plate depending from the underside of said
mounting plate means;
a second stabilizing plate depending from the underside of said
mounting plate means;
bracket means for mounting said mounting plate means to said gas
chromatograph, said bracket means being secured to said gas
chromatograph adjacent said injection site so as to permit access
to said injection site by said autosampler, said bracket means
including:
a first bracket secured to said gas chromatograph on one side
injection site, said first bracket including:
an inner edge facing said injection site;
an angled cut-out section in alignment with said spacer and
extending from said inner edge, so as to permit access of said
spring means through said second hole of said mounting plate means
and about said spacer to thereby removably secure said injector on
said mounting plate means;
a first cut-out section for receivintg said first stabilizing plate
to stabilize said mounting plate means and said injector on said
bracket means;
a second bracket secured to said gas chromatograph on an opposite
side of said injection site, said second bracket including:
an inner edge facing said injection site;
a second cut-out section for receiving said second stabilizing
plate to stabilize said mounting plate means and said injector on
said bracket means; and
securement means for securing said mounting plate means on said
bracket means, said securement means including:
a first hole in said first bracket;
a second hole in said second bracket;
a third hole in said mounting plate means in alignment with said
first hole when said mounting plate means is positioned on said
bracket means;
a fourth hole in said mounting plate means in alignment with said
third hole when said mounting plate means is positioned on said
bracket means;
a first securing screw extending through said first and third
holes; and
a second securing screw extending through said second and third
holes, wherein said first and second securing screws secure said
mounting plate means on said bracket means with a two-point
securement.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to gas chromatography, and more
particularly, is directed to the automation of sample injections in
a gas chromatograph.
Nitroglycerin assays are performed by gas chromatographic analysis
of nitroglycerin in plasma, using electron capture detection.
Originally, such nitroglycerin analyses were carried out using
packed column gas chromatography. Recently, however, state of the
art capillary gas chromatography has been used for such
analyses.
When performing such nitroglycerin assays with state of the art gas
chromatographs, it is generally required that the gas chromatograph
provide a sensitivity which permits detection of the nitroglycerin
to a level of 25 picograms/milliliter (pg/ml) of plasma. It has
been found that the VISTA 6000 model gas chromatograph sold by
Varian Associates, Inc., 611 Hansen Way, Palo Alto, Calif. 94303,
gives excellent sensitivity and meets this requirement.
Varian presently sells an autosampler for use with its gas
chromatograph. The autosampler mounts on the gas chromatograph and
provides automatic, multiple sample injections to an injection port
of the gas chromatograph. However, the Varian autosampler requires
at least 50 microliters (.mu.l) of sample for one injection. In
certain circumstances, however, such as the aforementioned
nitroglycerin assays, it may be required that the autosampler
perform multiple injections with the same sample when only 50 .mu.l
or less of sample volume is available. This means that samples must
be prepared again.
Therefore, it has been necessary to manually inject the samples
when performing nitroglycerin assays. As a result, hours of
valuable research time have been spent peforming routine sample
injections. Consequently, laboratory personnel have been required
to work overtime to complete analyses, resulting in physical and
mental fatigue.
Hewlett-Packard sells an autosampler (HP 7673A Automatic Sampler)
which can perform multiple injections with a sample volume of less
than 50 .mu.l. This is because the Hewlett-Packard autosampler does
not use the entire sample during one injection. The Hewlett-Packard
autosampler, however, cannot be mounted directly on the Varian
VISTA 6000 gas chromatograph.
OBJECTS AND SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a
gas chromatograph/autosampler coupling assembly that overcomes the
aforementioned problems with the prior art.
It is another object of the present invention to provide a gas
chromatograph/autosampler coupling assembly that permits automatic
processing of nitroglycerin assays twenty four hours per day.
It is still another object of the present invention to provide a
gas chromatograph/autosampler coupling assembly that substantially
reduces the time and cost of processing nitroglycerin assays.
It is yet another object of the present invention to provide a gas
chromatograph/autosampler coupling assembly that reduces operator
fatigue and errors, resulting in the production of higher quality
data.
It is a further object of the present invention to provide a gas
chroatograph/autosampler coupling assembly that is inexpensive to
manufacture and use.
In accordance with an aspect of the present invention, an assembly
for coupling an autosampler mounted on a mounting plate, to a gas
chromatograph having an injection site, includes bracket means for
mounting the mounting plate to the gas chromatograph, the bracket
means being secured to the gas chromatograph adjacent the injection
site so as to permit access to the injection site by the
autosampler; and securement means for securing the mounting plate
on the bracket means.
In accordance with another aspect of the present invention, an
assembly for coupling an autosampler to a gas chromatograph having
an injection site, includes mounting plate means for holding the
autosampler; bracket means for mounting the mounting plate means to
the gas chromatograph, the bracket means being secured to the gas
chromatograph adjacent the injection site so as to permit access to
the injection site by the autosampler; and securement means for
securing the mounting plate means on the bracket means.
In accordance with still another aspect of the present invention,
an assembly is provided for coupling an autosampler to a gas
chromatograph having an injection site, the gas chromatograph
including a septum nut assembly at the injection site, the auto
sampler including an injector having a base with an opening, spring
means extending from the base and an injector pin extending from
the base, the assembly including
mounting plate means for holding the autosampler, the mounting
plate means including a first opening for permitting the septum nut
to mate in the opening in the base of the autosampler; a second
opening; a spacer secured to the mounting plate means and extending
into the second opening; an arcuate slot for receiving the injector
pin when the injector is mounted on the mounting plate means; a
first stabilizing plate depending from the underside of the
mounting plate means; a second stabilizing plate depending from the
underside of the mounting plate means;
bracket means for mounting the mounting plate means to the gas
chromatograph, the bracket means being secured to the gas
chromatograph adjacent the injection site so as to permit access to
the injection site by the autosampler, the bracket means
including
a first bracket secured to the gas chromatograph on one side of the
injection site, the first bracket including an inner edge facing
the injection site; an angled cut-out section in alignment with the
spacer and extending from the inner edge, so as to permit access of
the spring means through the second hole of the mounting plate
means and about the spacer to thereby removably secure the injector
on the mounting plate means; a first cut-out section for receiving
the first stabilizing plate to stabilize the mounting plate means
and the injector on the bracket means;
a second bracket secured to the gas chromatograph on an opposite
side of the injection site, the second bracket including an inner
edge facing the injection site; a second cut-out section for
receiving the second stabilizing plate to stabilize the mounting
plate means and the injector on the bracket means; and
securement means for securing the mounting plate means on the
bracket means, the securement means including a first hole in the
first bracket; a second hole in the second bracket; a third hole in
the mounting plate means in alignment with the first hole when the
mounting plate means is positioned on the bracket means; a fourth
hole in the mounting plate means in alignment with the third hole
when the mounting plate means is positioned on the bracket means; a
first securing screw extending through the first and third holes;
and a second securing screw extending through the second and third
holes, wherein the first and second securing screws secure the
mounting plate means on the bracket means with a two-point
securement.
The above and other objects, features and advantages of the present
invention will become readily apparent from the following detailed
description which is to be read in connection with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of apparatus for performing automatic
gas chromatograph assays according to the present invention;
FIG. 2 is a perspective view of the quadrant trays of the
autosampler of FIG. 1;
FIG. 3 is a perspective view of the tray base and mounting plate of
the autosampler of FIG. 1;
FIG. 4 is a perspective view showing the assembly of the injector
of the autosampler of FIG. 1 onto the mounting plate;
FIG. 5 is a perspective view of one bracket of the coupling
assembly of FIG. 1;
FIG. 6 is a perspective view of the other bracket of the coupling
assembly of FIG. 1;
FIG. 7 is a side elevational view of the bracket of FIG. 5;
FIG. 8 is a top plan view of the bracket of FIG. 5;
FIG. 9 is an end elevational view of the bracket of FIG. 5;
FIG. 10 is a top plan view of the bracket of FIG. 6;
FIG. 11 is a side elevational view of the bracket of FIG. 6;
FIG. 12 is an end elevational view of the bracket of FIG. 6;
FIG. 13 is a perspective view of the gas chromatograph of FIG.
1;
FIG. 14 is an enlarged perspective view of a portion of the gas
chromatograph of FIG. 13, with the brackets of FIGS. 5 and 6
secured thereon;
FIG. 15 is an enlarged perspective view of the portion of the gas
chromatograph of FIG. 14, with the mounting plate mounted on the
brackets;
FIG. 16 is an enlarged perspective view of the portion of the gas
chromatograph of FIG. 15, with a tray mounted on the mounting
plate;
FIG. 17 is an enlarged perspective view of the portion of the gas
chromatograph on FIG. 16, with the injector mounted on the tray and
the mounting plate; and
FIG. 18 is an enlarged perspective view of the gas chromatograph of
FIG. 13, with the autosampler mounted thereon.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
Referring to the drawings in detail, and initially to FIG. 1
thereof, apparaus 10 for performing automatic gas chromatograph
assays generally includes a gas chromatograph 12, an autosampler 14
and a coupling assembly 16 for coupling the gas chromatograph 12 to
autosampler 14.
More specifically, in a preferred embodiment of the present
invention, gas chromaytograph 12 is a VISTA 6000 gas chromatograph
sold by Varian Associates, Inc., 611 Hansen Way, Palo Alto, Calif.
94303. The Varian gas chromatograph uses two microprocessors (not
shown) to provide a dual channel instrument and is composed of
three basic modules mounted on a common base 18. Specifically,
there is a lower electronics module 20, a pneumatics module 22 and
a main frame module 24, the latter including a multi-ramp
programmable column oven 26 and an upper electronics cabinet 28.
Lower electronics module 20 and upper electronics cabinet 28
include various printed circuit boards (not shown) for controlling
the operation of gas chromatograph 12, with upper electronics
cabinet 28 being provided with various control knobs and switches
30. Pneumatics module 22 contains the filters, digital flow
controllers, pressure regulators, air/H.sub.2 valves, make-up
valves, pressure gauges, cryogenic valves and column-switching
actuators. Column oven 26 is located behind a column oven door 32
and underneath instrument top covers 34.
Further, gas chromatograph 12 includes a detector cabinet 36
installed above column oven 26 of main frame module 24, and which
includes, for example, a thermal conductivity detector, an electron
capture detector and the like. The detectors of detector cabinet 36
profect through the top of and into column oven 26.
Gas chromatograph 12 can be controlled by a computer system 38,
such as the VISTA 402 data system sold by Varian, which includes a
cathode ray tube (CRT) 40 and keyboard 42. Computer system 38
executes automation and external event applications, and can
process, store, and print peak data and reports.
For purposes of the present invention, a detailed description of
the above components of the Varian gas chromatograph 12 is
unnecessary.
Varian gas chromatograph 12 further includes injectors and injector
ovens (not shown) located beneath instrument top covers 34. In the
VISTA 6000 model gas chromatograph, one injector is located on each
side of the apparatus, each equidistant from detector cabinet 36.
An injector cover 44 is positioned on each instrument top cover 34,
in covering relation to the respective injector, with each injector
cover including an injection site or port 46. In this manner, a
needle (not shown) containing a sample can be injected through each
site 46 into the respective injector in order to perform a gas
chromatographic analysis with respect to the same.
As described above, Varian does sell an auto sampler for use with
Varian gas chromatograph 12. The autosampler mounts on Varian gas
chromatograph 12 and provides automatic, multiple sample injections
to an injection port 46. Thus, if automatic injection is required,
a predrilled and fitted instrument top cover (not shown) is
provided for gas chromatograph 12 to permit proper mounting of the
autosampler. However, as also described above, such autosampler is
unsuitable for use with Varian gas chromatograph 12 when using the
latter for nitroglycerin assays.
As described above, the Varian autosampler requires at least 50
microliters (.mu.l) of sample for one injection. However, when
performing nitroglycerin assays, it may be required that the
autosampler perform multiple injections with the same sample when
only 50 .mu.l or less of sample volume is available. This means
that, with the Varian autosampler, samples must be prepared again.
Therefore, it has been necessary to manually inject the samples
when performing nitroglycerin assays. As a result, hours of
valuable research time have been spent performing routine sample
injections. Consequently, laboratory personnel have been required
to work overtime to complete analyses, resulting in physical and
mental fatigue.
Hewlett-Packard sells and autosampler (HP 7673A Automatic Sampler)
which can perform multiple injections with a sample volume of less
than 50 .mu.l. This is because the Hewlett-Packard autosampler does
not use the entire sample during one injection.
Specifically, as shown in FIGS. 1 and 2, the Hewlett-Packard
autosampler 14 includes a circular tray 48 which functions as the
storage and transportation vehicle for up to 100 sample vials. Tray
48 is formed by four removable quadrant trays 50, each quadrant
tray 50 containing five rows of five recesses 52, each recess 5i
adapted to contain a sample vial, and with all four trays 50
mounted on a circular tray base 54 (FIGS. 2 and 3). Quadrant trays
50 are formed as hollow plastic molded parts so as to provide
passages (not shown) for circulation of fluid for moderate
temperature control of the sample vials.
A transport mechanism 56 is positioned on tray base 54 at the
center of quadrant trays 50, and includes an arm 58 and a gripper
60 at the end of arm 58 for gripping the vials stored on trays 50.
Transport mechanism 56 is capable of movement in three directions,
that is, radially, about its axis and vertically. Specifically, arm
58 can move in the radial and axial direction, while gripper 60 can
move in the vertical direction. When picking up a vial, arm 58
positions gripper 60 beside the vial, then rotates to snap to claw
62 of gripper 60 onto the neck of the vial. The individual sample
vials are moved from tray 48 to the injector 64 of Hewlett-Packard
autosampler 14, and back, by the transport mechanism 56.
Injector 64 normally mounts to a mounting plate 66 directly over
the injection port 46 of a Hewlett-Packard gas chromatograph, as
shown in FIG. 4. Mounting plate 66 is formed in a substantially
Z-configuration with a horizontal securing plate section 70 to
which circular tray base 54 is mounted and secured, a short
vertical plate section 72 extending downwardly from one free end of
securing plate section 70, and a horizontal mounting plate section
74 extending from the opposite free end of vertical plate section
72, with mounting plate section 74 being positioned and secured
over the injection site or port 46.
As shown in FIG. 4, a septum nut 77 at the injection site or port
46 extends through an opening 76 in mounting plate section 74 and
through an opening 78 in the base 80 of injector 64, as indicated
by arrow A, to provide precise alignment. A syringe needle (not
shown) is provided in opening 78 for supplying the sample to
injection site 46. In addition, a bayonet spring clip 82 on the
bottom of injector 64 engages a locating hole 84 in mounting plate
section 74, as indicated by arrow B. As will be appreciated,
bayonet spring clip 82 extends through locating hole 84 and engages
the underside of mounting plate section 74. In order to increase
the spring action of bayonet spring clip 82, a spacer 83 is secured
to mounting plate section 74 and extends into locating hole 84 to
effectively increase the width of mounting plate section 74
thereat, and thereby, increase the extent to which bayonet spring
clip 82 is biased at the underside of mounting plate section 74.
Further, an alignment pin 86 on the bottom of injector 64 engages a
locating slot 88 in mounting plate section 74. When the above
assembly has been completed, and with the base 80 of injector 64
resting flat on mounting plate section 74, which is normally
located on the Hewlett-Packard gas chromatograph, injector 64 is
turned one-eight turn clockwise until injector 64 is locked in
place.
In addition, two rectangular openings 87 and 89 are provided in
horizontal mounting plate section 74, and a T-shaped stabilizing
plate 91 is secured in each opening 87 and 89.
Further, tray base 54 has a center post (not shown) at its
underside, which fits within a slot 90 in securing section 70 until
the peripheral edge of tray base 54 fits beneath circular stops 92
thereon, as shown in FIG. 3. As shown best in FIGS. 15 and 16, slot
90 effectively creates two parallel, bifurcated arms 97 and 99 of
securing section 70.
In order to control the operation of the Hewlett-Packard
autosampler 14, a Hewlett-Packard autosampler controller 94 is
connected with transport mechanism 56 and injector 64, and a
Hewlett-Packard 3393A integrator 96 is connected with controller
94. Thus, integrator 96, through controller 94, provides a sequence
which is a set of parameters which guides autosampler 14 through a
series of injections to gas chromatograph 12. A sequence always
references a method file or uses the active method parameters to
define the operation of the autosampler. Together, a method and a
sequence determine how a series of analyses are to be carried
out.
Thus, with the Hewlett-Packard autosampler 14, 1 to 100 samples may
be automatically injected into the gas chromatograph.
However, as discussed above, there is no provision for mounting
Hewlett-Packard autosampler 14 directly on the Varian VISTA 6000
gas chromatograph 12.
The present invention overcomes this problem by providing coupling
assembly 16 for connecting a Hewlett-Packard autosampler 14
directly on a Varian VISTA 6000 gas chromatograph 12 in order to
provide a gas chromatograph with the necesary sensitivity coupled
with an autosampler that can perform multiple injections on the
same sample when only 50 .mu.l of sample volume is available.
Specifically, coupling assembly 16 is formed by two brackets 100
and 102, as shown in FIGS. 5-12. Bracket 100 is formed as a
substantially L-shaped bracket having a horizontal leg plate 104
and a vertical leg plate 106 extending downwardly from one
lengthwise edge 108 of horizontal leg plate 104.
As shown best in FIG. 8, horizontal leg plate 104 includes opposite
and parallel lengthwise edges 108 and 110 having lengths of 27.0
centimeters (cm) and 30.5 cm, respectively. At one end of
lengthwise edge 108, a single inwardly directed step 112 is formed
having a widthwise step edge 114 of 0.4 cm and a lengthwise step
edge 116 of 1.8 cm. Widthwise step edge 114 is perpendicular to
lengthwise edge 108 and lengthwise step edge 116 is parallel to
lengthwise edge 108. A transverse edge 118 of horizontal leg plate
104, having a dimension of 3.4 cm, connects the end of lengthwise
step edge 116 to one end of lengthwise edge 110 and is
perpendicular thereto.
At the opposite end of lengthwise edge 108, two inwardly directed
steps 120 and 122 are formed. Specifically, step 120 is formed
having a widthwise step edge 124 of 0.5 cm and a lengthwise step
edge 126 of 0.9 cm, followed by step 122 having a widthwise step
edge 128 of 1.2 cm and a lengthwise step edge 130 of 0.8 cm.
Widthwise step edges 124 and 128 are perpendicular to lengthwise
edge 108 and lengthwise step edges 126 and 130 are parallel to
lengthwise edge 108. A transverse edge 132 of horizontal leg plate
104, having a dimension of 2.2 cm, connects the end of lengthwise
step edge 130 to the opposite end of lengthwise edge 110 and is
perpendicular thereto.
Further, horizontal leg plate 104 includes a rectangular cut-out
section 134 having widthwise cut-out edges 136 and 138 of 1.4 cm
and a lengthwise cut-out edge 140 of 4.0 cm. The last lengthwise
cut-out edge is formed in line with lengthwise edge 108. Cut-out
edge 136 is formed a distance of 10.8 cm from widthwise step edge
114, and cut-out edge 138 is formed a distance of 12.2 cm from
widthwise step edge 124.
An angled cut-out section 142 is formed at the opposite edge 110 of
horizontal leg plate 104. Specifically, angled cut-out section 142
includes a first angled cut-out edge 144 extending inwardly from
lengthwise edge 110 for a distance of 4.0 cm, starting at a
distance of 9.2 cm from transverse edge 118, and angled at
approximately 33 degrees with respect to lengthwise edge 110 away
from transverse edge 118. Angled cut-out section 142 further
includes a second angled cut-out edge 146 extending inwardly from
lengthwise edge 110 for a distance of 1.9 cm, starting at a
distance of 18.8 cm from transverse edge 132, and angled at
approximately 33 degrees with respect to lengthwise edge 110 away
from transverse edge 118. Thus, angled cut-out edges 144 and 146
are parallel to each other and spaced from each other by a distance
of 2.5 cm. The inward ends of angled cut-out edges 144 and 146 are
connected together by a cut-out edge 148 of 1.4 cm and which is
perpendicular to angled cut-out edges 144 and 146.
Finally, horizontal leg plate 104 includes two circular holes 150
and 152. Hole 150 is a 3/16 inch diameter hole formed with its
center 2.75 cm from lengthwise edge 110 and 0.6 cm from transverse
edge 118, and is provided to secure bracket 100 to an existing hole
in the Varian VISTA 6000 gas chromatograph 12, with a screw. Hole
152 is sized to receive a 1/8 inch self tapping screw and is formed
with its center 1.6 cm from lengthwise edge 110 and 6.3 cm from
transverse edge 132. Hole 152 is provided to secured the
Hewlett-Packard autosampler 14 thereto.
As best shown in FIG. 7, vertical leg plate 106 is formed as a
rectangular plate with upper and lower lengthwise edges 154 and 156
of 27.0 cm and widthwise edges 158 and 160 of 1.9 cm, with
widthwise edge 158 being in-line with widthwise step edge 124 and
forming a continuation thereof, with widthwise edge 160 being
in-line with widthwise step edge 114 and forming a continuation
thereof, and with upper lengthwise edge 154 being identical, that
is colinear with, lengthwise edge 108 of horizontal leg plate
104.
In addition, vertical leg plate 106 is formed with a rectangular
cut-out section 162 formed as a continuation of rectangular cut-out
section 134. Specifically, rectangular cut-out section 162 is
formed with widthwise cut-out edges 164 and 166 of 1 cm, which are
continuations of and in-line with widthwise cut-out edges 136 and
138, respectively. Widthwise cut-out edge 164 starts at upper
lengthwise edge 154 a distance of 10.8 cm from widthwise edge 160
and is perpendicular to upper lengthwise edge 154. Widthwise
cut-out edge 166 starts at upper lengthwise edge 154 a distance of
12.2 cm from widthwise edge 158 and is perpendicular to upper
lengthwise edge 154. The lower ends of widthwise cut-out edges 164
and 166 are connected by a lower lengthwise cut-out edge 168 which
is parallel to lengthwise edge 154 and has a dimension of 4.0
cm.
Bracket 102 is also formed as a substantially L-shaped bracket
having a horizontal leg plate 170 and a vertical leg plate 172
extending downwardly from one lengthwise edge 174 of horizontal leg
plate 170.
As shown best in FIG. 10, horizontal leg plate 170 includes
opposite and parallel lengthwise edges 174 and 176 having lengths
of 28.7 cm and 30.5 cm, respectively. At one end of lengthwise edge
174, a single inwardly directed step 178 is formed having a
widthwise step edge 180 of 1.2 cm and a lengthwise step edge 182 of
1.8 cm. Widthwise step edge 180 is perpendicular to lengthwise edge
174 and lengthwise step edge 182 is parallel to lengthwise edge
174. A transverse edge 184 of horizontal leg plate 170, having a
dimension of 2.5 cm, connects the end of lengthwise step edge 182
to one end of lengthwise edge 176 and is perpendicular thereto. A
transverse edge 185 connects the opposite ends of lengthwise edges
174 and 176 and has a dimension of 3.7 cm. Transverse edges 184 and
185 are perpendicular to lengthwise edges 174 and 176.
Further, horizontal leg plate 170 includes a rectangular cut-out
section 186 having widthwise cut-out edges 188 and 190 of 1.7 cm
and a lengthwise cut-out edge 192 of 1.3 cm. The last lengthwise
cut-out edge is formed in line with lengthwise edge 176. Cut-out
edge 188 is formed a distance of 4.0 cm from transverse edge 185,
and cut-out edge 190 is formed a distance of 25.2 cm from
transverse edge 184.
Horizontal leg plate 170 also includes two circular holes 194 and
196. Hole 194 is a 3/16 inch diameter hole formed with its center
1.9 cm from lengthwise edge 176 and 0.6 cm from transverse edge
184, and is provided to secure bracket 102 to an existing hole in
the Varian VISTA 6000 gas chromatograph 12, with a screw or bolt.
Hole 196 is sized to receive a 1/8 inch self tapping screw and is
formed with its center 3.4 cm from lengthwise edge 174 and 0.9 cm
from widthwise cut-out edge 190. Hole 196 is provided to secure the
Hewlett-Packard autosampler 14 thereto.
Finally, horizontal leg plate 170 is formed with a sime-circular
slot 198 having a radial dimension of 0.2 cm, at lengthwise edge
176. The center of slot 198 is spaced 7.6 cm from transverse edge
184. Slot 198, along with a both, nut and washer, is provided to
secure the Hewlett-Packard autosampler 14 thereto.
As best shown in FIG. 11, vertical leg plate 172 is formed as a
rectangular plate with upper and lower lengthwise edges 200 and 202
of 26.3 cm and widthwise edges 204 and 206 of 1.9 cm, with
widthwise edge 204 being in-line with widthwise step edge 180 and
forming a continuation thereof, and with upper lengthwise edge 200
being identical, that is, collinear with, lengthwise edge 174 of
horizontal leg plate 170.
In addition, bracket 102 is formed with an L-shaped tab 208
immediately adjacent widthwise edge 206 of vertical leg plate 172.
Tab 208 thereby includes a horizontal tab section 209 of a
rectangular configuration, with opposite widthwise tab edges 210
and 212 of 1.0 cm, a lengthwise tab edge 214 of 1.0 cm which
connects the ends to tab edges 210 and 212, and another lengthwise
tab edge which forms part of lenthwise edge 174 of horizontal leg
plate 170. Widthwise tab edge 212 is spaced 1.4 cm from transverse
edge 185. Tab 208 further includess a downwardly extending vertical
tab section 216 of a rectangular configuration connected at tab
edge 214, with opposite widthwise tab edges 218 and 220 of 1.9 cm,
a lenthwise tab edge 222 of 1.0 cm which connects the ends of tab
edges 218 and 220, and another lengthwise tab edge which is
identical to lengthwise tab edge 214.
A description will now be given with respect to FIGS. 13-18 as to
the assembly of Hewlett-Packard autosampler 14 with a Varian VISTA
6000 gas chromatograph 12. Specifically, a Varian gas chromatograph
12 is shown in FIG. 13 with its instrument top covers disassembled
therefrom so as to completely expose injection port 46 and septum
nut 77. As shown best in FIG. 14, two transverse support shelves
230 and 232 are secured at the front and rear portions of Varian
gas chromatograph 12, on opposite sides of each injection port 46.
Bracket 100 according to the present invention is secured on top of
shelves 230 and 232, extending transversely across such shelves 230
and 232 and to one side thereof. In like manner, bracket 102
according to the present invention is secured on top of shelves 230
and 232, extending transversely across such shelves 230 and 232 and
to the opposite side thereof, with bracket 102 being spaced from
and arranged parallel to bracket 100. It will be appreciated that,
with this arrangement, brackets 100 and 102 and shelves 230 and 232
are arranged effectively in a rectangular configuration, with
septum nut 77 positioned substantially centrally therein. In order
to secure brackets 100 and 102 in such position, bolts or screws
234 and 236 extend through holes 150 and 194 in brackets 100 and
102, respectively, and are threadedly received in threaded holes
238 and 240 in shelf 232.
Further, with this arrangement, brackets 100 and 102 are arranged
such that angled cut-out section 142 of bracket 100 is on the inner
side of bracket 100 facing bracket 102 and cut-out section 134 is
on the opposite outer side thereof, and cut-out section 186 of
bracket 102 is on the inner side of bracket 102 facing bracket 100.
In addition, lengthwise step edge 182 of bracket 102 is dimensioned
so that widthwise step edge 180 is immediately adjacent the
lengthwise inner edge 242 of shelf 232. Still further, with such
arrangement, tab 208 extendss down adjacent one end (not shown) of
shelf 230.
Thereafter, as shown in FIG. 15, mounting plate 66 is secured
thereover. Specifically, horizontal mounting plate section 74 is
positioned over brackets 100 and 102, with horizontal securing
plate section 70 being positioned above the upper surface of lower
electronics module 20. In this regard, slot 244 and hole 246 (FIG.
3) in horizontal mounting plate section 74 are aligned with holes
152 and 196 of brackets 100 and 102, respectively. Accordingly,
bolts or screws 248 and 250 extend through slot 244 and holes 246,
and are threadedly received in holes 152 and 196 to secure
horizontal mounting plate section 74 in position. It will be
appreciated from FIG. 15, that in this position, the leftmost
portion of horizontal mounting plate section 74 rests on the upper
surface of lower electronics module 20 for support. At the same
time, a bolt 252 is received in a hole 254 (FIG. 3) of horizontal
mounting plate section 74. In this manner, bolt 252 fits within
slot 198 in bracket 102 and provides stability to horizontal
mounting plate section 74.
It will further be appreciated that spacer 83 is in alignment with,
and fits within, angled cut-out section 142 of bracket 100. Also,
T-shaped stabilizing plate 91 in rectangular opening 87 of mounting
plate section 74 fits snugly withing rectangular cut-out section
134, while T-shaped stabilizing plate 91 in rectangular opening 89
fits snugly within rectangular cut-out section 186, thereby further
stabilizing horizontal mounting plate section 74.
A plastic rectangular tray 258 having a bottom 260, and three side
walls 262, 264 and 266, is mounted on top of horizontal mounting
plate section 74, as shown in FIG. 16, with the front of tray 258
being open. Tray 258 includes a hole 268 in alignment with opening
76 of horizontal mounting plate section 74, an elongated slot 270
in alignment with hole 84 and spacer 83, and an elongated slot 272
in alignment with slot 88. In this manner, septum nut 77 and
opening 78 in base 80 mate through opening 76 in horizontal
mounting plate section 74 and hole 268 in tray 258. In addition,
bayonet spring clip 82 extends through slot 270 and hole 84, and
alignment pin 86 extends through slots 272 and 88, wherein base 80
of injector 64 rests on the upper surface of tray 258. It will be
appreciated that a major purpose of tray 258 is to effectively
increase the width of horizontal mounting plate section 74 to
further bias bayonet spring clip 82, and thereby increase the
spring force thereby in the assembled condition so as to enhance
the stability of injector 64 on tray 258.
As shown in FIG. 17, injector 64 is then assembled in place on top
of tray 258 in the manner previously described with respect to FIG.
4. Then, circular tray 48 is positioned on horizontal securing
plate section 70 such that a lower center post (not shown) thereof
extends in slot 90 and with the peripheral edge of tray base 54
positioned under, and held down by, stops 92. Thereafter, all of
the appropriate electrical connections are made with conduit 300
shown in FIG. 17.
Thus, with apparatus 10 described above, in which a Varian VISTA
6000 gas chromatograph 12 and a Hewlett-Packard autosampler 14 are
combined by coupling assembly 16, apparatus 10 operates as an
integrated gas chromatography system. The sequence of operation
begins by entering operating parameters on the Varian VISTA 6000
gas chromatograph. Gas chromatograph 12 stabilizes to the setpoint
conditions, such as oven temperature, detector temperature, and the
like, and thereafter advances to the ready state. Data collection
parameters, such as the sample identification numbers, are then
entered on the Varian VISTA 402 data system 38, which is then
prepared for data collection. Finally, the Hewlett-Packard
autosampler 14 is readied for an injection sequence by entering
operating parameters, such as the sample volume, the number of
vials, the stop time, and the like, through the Hewltt-Packard
3393A integrator 96.
When all systems are ready, autosampler 14 is started and a sample
is injected. As the injection is made, the syringe barrel depresses
a start switch located directly above the injector nut, and the gas
chromatograph run sequence and data collection operations begin. To
ensure contact of the syringe barrel with the start switch, a
septum with a hole is adhered to the start switch. The septum also
provides a cushioned interface between the syringe barrel and start
switch. The autosampler 14 is operated in the on-column injection
mode, rather than in the split/splitless mode. This is because,
when operated in the injection mode, the syringe barrel lowers
itself 19 mm lower than in the split/splitless mode. When the
analysis is complete, gas chromatograph 12 and data system 38 ready
themselves for the next injection, and so on.
With the above combination of a Varian VISTA 6000 gas chromatograph
12 and a Hewlett-Packard autosampler 14, processing of
nitroglycerin assays can be performed 24 hours per day. This
results in a significant savings of time and money. Further, there
is less operator fatigue, fewer errors, and thereby, higher quality
data, particularly when performing nitroglycerin analyses.
It will be appreciated that although the above discussion has been
provided with respect to the coupling of a Varian VISTA 6000 gas
chromatograph with a Hewlett-Packard autosampler, the present
invention has wider applicability, and it may be used to couple
other gas chromatographs and autosamplers which have prior to the
present invention been incompatible.
It will further be appreciated that, while two separate brackets
100 and 102 have been provided, the number of components can be
varied. For example, brackets 100 and 102 can be incorporated into
a single bracket provided with a central opening that approximates
the spacing between 100 and 102 in assembled condition.
As another alternative, although two brackets 100 and 102 have been
shown, bracket 100 can be eliminated. In such case, bolt 248 would
extend through another hole (not shown) in bracket 102 so as to
provide a two-point securement of horizontal mounting plate section
74 thereon, that is by bolts or screws 248 and 250 both extending
through bracket 102. In such case, horizontal mounting plate
section 74 would extend across bracket 102 and the upper surface of
lower electronics module 20.
Having described a specific preferred embodiment of the invention
with reference to the accompanying drawings, it will be appreciated
that the present invention is not limited to that precise
embodiment, and that various changes and modifications may be
effected therein by one of ordinary skill in the art without
departing from the scope or spirit of the invention as defined in
the appended claims.
* * * * *